package map;

import java.util.HashMap;
import java.util.Map;

public class MapDemo02 {
    public static void main(String[] args) {
        Map<String,String> map = new HashMap<>();
        map.put("qq","23");
        map.put("ww","23");
        map.put("ee","24");

        String s = map.put("qq", "25");
        System.out.println(s);

        map.remove("qq");
        boolean b = map.remove("ee", "25");
        System.out.println(b);
        System.out.println(map);
        System.out.println(map.containsKey("qq"));
        System.out.println(map.containsValue("22"));

        System.out.println(map.size());

        System.out.println(map.isEmpty());
        map.clear();;
        System.out.println(map.isEmpty());
    }
}
